Differential ability of alcohol fermentation between the seeds of flooding-tolerant and flooding-susceptible varieties of Echinochloa crus-galli (L.) Beauv.

Seed germination and respiratory metabolism under aerobic and anaerobic conditions were studied in the flooding-tolerant and flooding-susceptible varieties of Echinochloa crus-galli with an identical genome and common ancestry . In the flooding-tolerant E. crus-galli var. formosensis , the seeds imbibed under nitrogen could germinate and exhibited an I/N quotient > 0.6. They accelerated glycolysis and concomitantly produced large and equimolar quantities of carbon dioxide and ethanol, suggesting that the seeds of this variety showed operation of the Pasteur effect and respired through alcohol fermentation under anaerobic conditions. The seeds excreted most of the toxic fermentation product. In contrast, the seeds of the flooding-susceptible E. crus-galli var. praticola were capable of germinating only under aerobic conditions through the conventional aerobic respiration and were unable to anaerobically respire to germinate through alcohol fermentation regardless of the presence of both sufficient alcohol dehydrogenase activity and a high redox charge of the pyridine nucleotides.     

Development of a spot plow providing complete inversion for effective weed control

Tillage for the "complete inversion" of soil, that is, overturning soil slices 180° was proposed, a "spot plow" was developed and tested to accomplish the task, and a simulation model was evaluated to demonstrate the efficacy of the plow on weed control. A 360 mm wide spot plow was designed to operate at a speed of 1.9 m s⁻¹ for the spot plowing with the least possible lateral displacement of the soil slice by utilizing the inertia of the soil slice and securely rotating it. In field experiments, complete spot inversion required an operating speed of at least 1.6 m s⁻¹; at lower speeds, a portion of the soil block was left half-inverted and further lowering led to considerable lateral displacement. The displacement in the forward and lateral directions was minimal, implying that spot plowing is suitable for potential application to and verification of the weed population dynamics model in the field. A simple linear matrix model of the population dynamics of annual weeds was proposed, whereby four layers of soil were set to describe tillage and other ecological events. The effect of tillage on weed control was evaluated by the equilibrium reproduction rate allowed to sustain a stable population of weeds. The simulation model showed that alternately changing the depth of spot plowing had a significant effect on controlling weeds of low-survival-rate seeds, even when some incomplete inversion of the soil slice was taken into account.     

银杏种子UDPG焦磷酸化酶特性的研究

银杏(Ginkgo biloba L.)种子中UDPG PPlase最适温度为29-30℃,最适pH为7.5-80,二价阳离子中Zn~(2 )、Ba~(2 )对其活性影响较小.Mn~(2 )、Mg~(2 )、Ca~(2 )对其有明显影响,而Cu~(2 )、Pb~(2 )有强烈的抑制作用.银杏种子幼小至膨大期,UDPG PPlase活性较低;种子成熟期至贮藏初期,活性迅速而显著地增强;贮藏过程中活性保持较高水平.     

水稻白叶枯病防治技术研究

应用中国农科院最新研制的农用抗生素中生菌素研究了其对水稻白叶枯病的防治效果和应用技术。室内浸种试验表明,用中生菌素100mg/kg、在水温58℃下浸稻种48h,可全部杀死种子表面及内部的白叶枯病菌,切断了种子带菌传病的途径。田间试验表明,用中生菌素50mg/kg、水温55～60℃的药液浸种48h,再于秧苗3～4叶期和移栽前5～7d用中生菌素15mg/kg施药保护,田间白叶枯病可迟发生20d以上,其发病程度亦显著降低,对于轻病田或轻发生年份大田可免于防治;重病田或重发生年份于发病初期再用中生菌素15mg/kg防治1次,即可控制病情的发展。作者认为用中生菌素浸种及秧田期施药保护不仅改变了以往田间发病初期用药防治的策略,而且大大降低了防治费用,经济效益、社会效益及生态效益显著。     

Production of hybrid seed in a seed orchard of two larch species,Larix sibirica and Larix decidua

The larch seed orchard studied is intended to produce interspecific hybrid seed between Larix sibirica and Larix decidua. Only the L. sibirica clone (half of the grafts) in the orchard was intended to act as the seed parent, and the six L. decidua clones are pollinators. The proportion of hybrid seed produced was determined using Mdh3 locus as a genetic marker. The mean percentage of hybrid seed produced by the grafts of L. decidua was 93, but that of the hybrid seed produced by L. sibirica was only 18. The results can be explained by differences in flowering abundance. The grafts of L. sibirica produced several times more pollen than those of L. decidua. Contrary to the original plans, L. decidua should be used as the seed parent and L. sibirica only as the pollen parent in the studied seed orchard.     

生长调节剂在暖季型草坪中的研究应用

近年来,植物生长调节剂在草业中的研究应用已经成为草业工作者研究的一大热点.植物生长调节剂被广泛地研究应用于调节暖季型草坪草的营养生长、改善草坪质量、增强暖季型草坪草的抗逆性以及提高其种子的产量等方面,并且取得了一定成果.     

不同种衣剂处理对青瓜生长及产量影响的研究

为探讨几种新型种衣剂在青瓜种子上的应用效果,研究了先正达迈舒平、氟虫腈、路明卫、高巧4种种衣剂对青瓜生长势、产量及抗病性的影响。结果表明:4种供试种衣剂均能不同程度地影响青瓜生长发育、产量及病害抗性。综合考虑生长势、产量等因素,表现为高巧悬浮种衣剂>先正达迈舒平悬浮种衣剂>氟虫腈悬浮种衣剂>路明卫悬浮种衣剂;在霜霉病、疫病的综合抗性上,表现为路明卫悬浮种衣剂>氟虫腈悬浮种衣剂>先正达迈舒平悬浮种衣剂>高巧悬浮种衣剂,4种供试种衣剂处理均能在一定程度上抑制霜霉病、疫病的发生。     

塔里木河下游不同地下水埋深下的土壤种子库特征

本研究根据长期地下水位的监测资料和土壤种子库的萌发试验,分析了塔里木河下游不同地下水埋深下植物样地土壤种子库特征。结果显示,在干旱地区,地下水埋深的高低不仅影响地上植被群落的种类和组成,而且也对土壤种子库的密度和组成具有明显的影响。随着地下水埋深逐渐下降,种子库密度减少、物种多样性下降、生活型逐渐单一。同时地上植被群落与土壤种子库的相似性系数也逐渐降低。本研究不仅有助于丰富国内外关于干旱区土壤种子库的理论研究,而且有利于指导塔里木河下游正在开展的大规模生态恢复实践。     

一串红良种繁育技术的研究

应2008奥运会的需求,象征中国喜庆的红色花卉的繁育成为热点。本文提出一串红的良种繁育制度和种子生产技术规程,并以新品种的良种繁育为核心,开展了相关研究,以供良种的繁育。     

不同土壤水分条件下硅对坪用高羊茅种子出苗及生物学特性的影响

水肥耦合不仅可以维持草坪草的正常生长,而且可以减少一定的灌溉量。采用盆栽试验研究了不同土壤条件下硅对坪用高羊茅种子出苗及生长的影响。结果表明,不添加硅时,高羊茅种子适宜出苗时的土壤含水量应为饱和含水量的４５％～６０％,植株生长适宜的土壤含水量应为饱和含水量的７５％以上;当土壤含水量大于或等于饱和含水量的６０％时,添加硅不仅能够提前坪用高羊茅种子的初始出苗时间,缩短集中出苗时期,提高出苗率,而且能够显著促进高羊茅的株高和叶长生长,增加地上和地下生物量（P＜０．０５）,而当土壤含水量小于或者等于饱和含水量的４５％时,添加硅对高羊茅种子出苗和生长发育没有明显影响,说明添加硅对坪用高羊茅生长的有益作用受土壤含水量的约束;土壤含水量为饱和含水量的６０％时,添加硅处理中植株的分蘖数、株高、叶长和生物量与对照处理中土壤含水量为饱和含水量的７５％时植株的分蘖数、株高、叶长和生物量差异不显著,说明添加硅能降低高羊茅植株正常生长所需的土壤含水量,有利于节约灌溉量。